(1) Modeling of wave propagation in cilia The objectives of this part include deriving the planar sliding filament model from specification of the three dimensional structure of the axoneme and, eventually, incorporating realistic models of the dynein cross bridge cycle. We also will construct a model for calcium controlled bend initiation and propagation and will incorporate this into the three dimensional system. (2) Realistic computer models of neurons (a) We seek to contribute to the understanding of some problems in neuron function which we find intriguing, i.e., how are analog signals transmitted along non-spiking axons and how does transmission at its termination differ from that at phasic synapses. b) Another problem is to gain further insight into the functioning of a phasic neuron by examining how its threshold for impulse initiation is mediated by the location and density of voltage sensitive channels as well as by temporal and spatial synaptic summation. (3) Computer methods and techniques for Physiology Objectives here are: a) the development of online setup and efficient solution of systems of nonlinear algebraic equations in order to facilitate development of targeted programs to deal with specific physiological problems; b) the development of special methods for simulation of propagation processes. (4) Collaboration and Training Collaboration will be established with other research labs having limited or no experience with computer simulations in order to develop new applications and train investigators in computer simulation techniques.